SATURATION LEVELS FOR WHITE-LIGHT FLARES OF FLARE STARS: VARIATION OF MINIMUM FLARE DURATION FOR SATURATION

Dal, H A; Evren, S

doi:10.1088/0004-6256/141/2/33

Title: SATURATION LEVELS FOR WHITE-LIGHT FLARES OF FLARE STARS: VARIATION OF MINIMUM FLARE DURATION FOR SATURATION

Full Record
Other Related Research

Abstract

Taking into account results obtained from models and from statistical analyses of obtained parameters, we discuss flare activity levels and flare characteristics of five UV Ceti stars. We present the parameters of unpublished flares detected over two years of observations of V1005 Ori. We compare parameters of the U-band flares detected over several seasons of observations of AD Leo, EV Lac, EQ Peg, V1054 Oph, and V1005 Ori. Flare frequencies calculated for all program stars and maximum energy levels of the flares are compared, and we consider which is the most correct parameter as an indicator of flare activity levels. Using the One Phase Exponential Association function, the distributions of flare equivalent duration versus flare total duration are modeled for each program star. We use the Independent Samples t-Test in the statistical analyses of the parameters obtained from the models. The results reveal some properties of flare processes occurring on the surfaces of UV Ceti type stars. (1) Flare energies cannot be higher than a specific value regardless of the length of the flare total duration. This must be a saturation level for white-light flares occurring in flare processes observed in the U band. Thus, for the first time itmore »« less

Authors:

Dal, H A; Evren, S ^[1]

Department of Astronomy and Space Sciences, University of Ege, Bornova, 35100 Izmir (Turkey)

Publication Date:: Tue Feb 15 00:00:00 EST 2011

OSTI Identifier:: 21583264

Resource Type:: Journal Article

Journal Name:: Astronomical Journal (New York, N.Y. Online)

Additional Journal Information:: Journal Volume: 141; Journal Issue: 2; Other Information: DOI: 10.1088/0004-6256/141/2/33; Journal ID: ISSN 1538-3881

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACTIVITY LEVELS; DATA ANALYSIS; HALF-LIFE; STARS; STELLAR FLARES; STELLAR ACTIVITY

Citation Formats


                    Dal, H A, and Evren, S. SATURATION LEVELS FOR WHITE-LIGHT FLARES OF FLARE STARS: VARIATION OF MINIMUM FLARE DURATION FOR SATURATION.  United States: N. p., 2011. 
        Web.  doi:10.1088/0004-6256/141/2/33.

Copy to clipboard


                    Dal, H A, & Evren, S. SATURATION LEVELS FOR WHITE-LIGHT FLARES OF FLARE STARS: VARIATION OF MINIMUM FLARE DURATION FOR SATURATION.  United States.  https://doi.org/10.1088/0004-6256/141/2/33

Copy to clipboard


                    Dal, H A, and Evren, S. 2011.  
        "SATURATION LEVELS FOR WHITE-LIGHT FLARES OF FLARE STARS: VARIATION OF MINIMUM FLARE DURATION FOR SATURATION".  United States.  https://doi.org/10.1088/0004-6256/141/2/33.

Copy to clipboard


                    
@article{osti_21583264,

  title        = {SATURATION LEVELS FOR WHITE-LIGHT FLARES OF FLARE STARS: VARIATION OF MINIMUM FLARE DURATION FOR SATURATION},

  author       = {Dal, H A and Evren, S},

  abstractNote = {Taking into account results obtained from models and from statistical analyses of obtained parameters, we discuss flare activity levels and flare characteristics of five UV Ceti stars. We present the parameters of unpublished flares detected over two years of observations of V1005 Ori. We compare parameters of the U-band flares detected over several seasons of observations of AD Leo, EV Lac, EQ Peg, V1054 Oph, and V1005 Ori. Flare frequencies calculated for all program stars and maximum energy levels of the flares are compared, and we consider which is the most correct parameter as an indicator of flare activity levels. Using the One Phase Exponential Association function, the distributions of flare equivalent duration versus flare total duration are modeled for each program star. We use the Independent Samples t-Test in the statistical analyses of the parameters obtained from the models. The results reveal some properties of flare processes occurring on the surfaces of UV Ceti type stars. (1) Flare energies cannot be higher than a specific value regardless of the length of the flare total duration. This must be a saturation level for white-light flares occurring in flare processes observed in the U band. Thus, for the first time it is shown that white-light flares have a saturation in a specific energy range. (2) The span values, which are the difference between the equivalent durations of flares with the shortest and longest total durations, are almost equal for each star. (3) The half-life values, minimum flare durations for saturation, increase toward the later spectral types. (4) Both maximum total durations and maximum rise times computed from the observed flares decrease toward the later spectral types among the UV Ceti stars. According to the maximum energy levels obtained from the models, both EV Lac and EQ Peg are more active than the other three program stars, while AD Leo is the most active flare star according to the flare frequencies.},

  doi          = {10.1088/0004-6256/141/2/33},

  url          = {https://www.osti.gov/biblio/21583264},
  journal      = {Astronomical Journal (New York, N.Y. Online)},

  issn         = {1538-3881},

  number       = 2,

  volume       = 141,

  place        = {United States},

  year         = {Tue Feb 15 00:00:00 EST 2011},

  month        = {Tue Feb 15 00:00:00 EST 2011}

}

Copy to clipboard

Journal Article:

https://doi.org/10.1088/0004-6256/141/2/33

Other availability

Find in Google Scholar

Search WorldCat to find libraries that may hold this journal

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

A NEW METHOD FOR CLASSIFYING FLARES OF UV Ceti TYPE STARS: DIFFERENCES BETWEEN SLOW AND FAST FLARES

Journal Article Dal, H; Evren, S - Astronomical Journal (New York, N.Y. Online)

In this study, a new method is presented to classify flares derived from the photoelectric photometry of UV Ceti type stars. This method is based on statistical analyses using an independent samples t-test. The data used in analyses were obtained from four flare stars observed between 2004 and 2007. The total number of flares obtained in the observations of AD Leo, EV Lac, EQ Peg, and V1054 Oph is 321 in the standard Johnson U band. As a result flares can be separated into two types, slow and fast, depending on the ratio of flare decay time to flare risemore »« less
https://doi.org/10.1088/0004-6256/140/2/483
AY Ceti: A flaring, spotted star with a hot companion

Journal Article Simon, T; Fekel, Jr, F; Gibson, D - Astrophys. J.; (United States)

AY Ceti is a late-type single-line spectroscopic binary, a bright X-ray source (L/sub x/roughly-equal1.5 x 10/sup 31/ ergs s/sup -1/), and a spotted star, as evidenced by its prominent photometric wave. In this paper, we report on observations made with the IUE satellite and the VLA radio interferometer. The 1200--2000 A UV spectrum of AY Cet shows a hot stellar continuum and a very broad Ly..cap alpha.. absorption line from a previously unobserved white dwarf secondary. The UV spectrum can be matched to the energy distribution of a (T/sub eff/ = 18,000 K, log g = 8) model atmosphere. Superposedmore »« less
https://doi.org/10.1086/163360
Dynamics of a flare current sheet. I. Diffusion thickening and estimated flare parameters

Journal Article Pustil'nik, L - Sov. Astron. AJ (Engl. Transl.), v. 19, no. 2, pp. 195-199

The process of magnetic-field dissipation in the current sheet of a solar-type flare is analyzed. Because of plasma turbulence, dissipation during the flare should take place through a splitting of the current sheet, followed by a diffusion thickening of the sheet. When the rate of thickening balances the rate of contraction due to outflow of plasma through the ends of the sheet, a steady equilibrium state will be established. It is noteworthy that the arrival velocity of the magnetic field at the current sheet, and thereby the power and duration of the flare energy release, here depend solely on themore »« less
Simultaneous radio and optical observations of UV Ceti-type flare stars

Journal Article Spangler, S; Moffett, T - Astrophys. J.; (United States)

The UV Ceti-type stars, YZ Canis Minoris, AD Leonis, and Wolf 524 AB, were monitored for 57.8 hours in the time interval 1974 January 15 to February 22 using the 1000 foot (305 m) radio telescope at Arecibo, Puerto Rico, and the 91 or 76 cm reflector at McDonald Obervatory of the University of Texas. Radio observations were made at frequencies of 430, 318, and 196 MHz, and optical monitoring was done in the Johnson U or B band, the Stromgren u band, or white light. During the period of simultanous observations, 62 optical flares were detected. A total ofmore »« less
https://doi.org/10.1086/154105
PROBING THE FLARE ATMOSPHERES OF M DWARFS USING INFRARED EMISSION LINES

Journal Article Schmidt, Sarah; Kowalski, Adam; Hawley, Suzanne; ... - Astrophysical Journal

We present the results of a campaign to monitor active M dwarfs using infrared spectroscopy, supplemented with optical photometry and spectroscopy. We detected 16 flares during nearly 50 hr of observations on EV Lac, AD Leo, YZ CMi, and VB 8. The three most energetic flares also showed infrared emission, including the first reported detections of P{beta}, P{gamma}, He I {lambda}10830, and Br{gamma} during an M dwarf flare. The strongest flare ({Delta}u = 4.02 on EV Lac) showed emission from H{gamma}, H{delta}, He I {lambda}4471, and Ca II K in the UV/blue and P{beta}, P{gamma}, P{delta}, Br{gamma}, and He Imore »« less
https://doi.org/10.1088/0004-637X/745/1/14

Similar Records